Penny Weight Set

I created these weights to work with my back to school balance scale (http://www.thingiverse.com/thing:152531). You can fill them with pennies to make them approximately equal to the following amounts:

20 grams
40 grams
50 grams
100 grams
200 grams
400 grams
500 grams.

I added the balance scale parts to this thing as well. Each US penny (minted after 1982) should weigh exactly 2.5 grams. So to fill the 500 gram weight, you need 200 pennies.